Process Control By Variable Drives

Abstract

The characteristics of some of the many alternative types of variable speed drive are discussed elsewhere in this book, and the purpose of this chapter is to analyse the reasons why such devices are important and are being increasingly used in modern industry. It is proposed to omit discussion of applications which are made after equipment has been in operation for some time, on the grounds that although some are installed for the valid reason that equipment is diverted to purposes other than those for which it was originally intended, many are effected because the advantages offered by the provision of variable speed were not foreseen at the outset. It is intended to indicate these advantages, so that variable speed may be considered at the design stage, as an essential design element.